i was pretty much setting my bike up to go through some deep mud bogs,but yet keep it somewhat trail friendly,and i think i accomplished both very well
i recommend wheel spacers period,,,it really helped planting the bike to the road,and trail,,,and also they widen the stance as far as getting "fresh bite" on heavily traveled trails,,,this means that most trails/ruts/mud holes were created by bikes with a somewhat standard wheel base,,the spacers help you get added traction while running through these areas by fully utilizing the side lugs on your tire,basically giving you twice the traction of a standard wheelbase bike,allowing you to get through with greater ease than them( not to mention the added stability)
i went with the 27" tires,basically because they were considerably larger over stock,and i felt the 28"s would be a lil extreme,keep in mind i still wanted to keep it somewhat trail friendly,since all of mud holes take some getting too
i really feel my end result,was what i was shooting for,,,i'm very pleased
they do make a 14" rim now,which the theory behind is,it allows you to go to a 28" tire without the loss of handling like you will see with a 12" rim,,,,,when you go to a 28" tire,on a 12" rim,the amount of sidewall is too much,which in turn gives your tire too much side to side flex,or balloon feeling,,,,,with the 14" rim,your making up for the larger tire with the rim itself,less side wall
i kept the 12" rims when i purchased them,because i was getting 2 sets of tires,and rims,so it was more cost effective to stay with the standard size,,,,if i had the extra dough,the 14" rims ARE the way to go (the 14" rims are type 7,,,,4,5,6 are 12" rims),,,keep in mind,the 14" rims are somewhat new,and i believe ITP are the only ones who make treads that fit (XTR's),,,pretty pricey